title: Oxidant inhibition of alphaLbeta2 integrin adhesion: evidence for coordinate effects on conformation and cytoskeleton linkage.
abstract: Dithiothreitol (DTT) and other dithiol antioxidants with closely spaced thiol pairs strongly activate leukocyte function antigen-1 (LFA-1, alphaLbeta2 integrin) to bind intercellular adhesion molecule-1 (ICAM-1). Because direct biochemical modification of LFA-1 by DTT is not apparently involved, we investigated the possible role of a reduction-oxidation (redox)-sensitive adhesion-regulatory pathway. Phenylarsine oxide (PAO), an oxidant selectively reactive with closely spaced pairs of thiol groups, inhibited LFA-1-dependent adhesion of human natural killer and HSB2 T leukemia cells to murine cells expressing human ICAM-1. PAO also induced disappearance of a conformation-sensitive LFA-1 epitope recognized by KIM127 antibodies and promoted an increase in total apparent cytoskeleton-linked LFA-1 in which a novel cytochalasin D-resistant linkage was involved. Exposure of PAO-pretreated cells to DTT caused a decline in LFA-1/cytoskeleton linkages in conjunction with rapid restoration of KIM127 epitope expression and LFA-1 adhesive function. Implicating an intracellular site of action were findings that (1) an epitope-tagged PAO probe bound predominantly to intracellular proteins but not detectably to immunoprecipitation-purified LFA-1 chains, and (2) membrane permeant but not impermeant dithiol antioxidants reversed PAO adhesion-inhibitory effects. These results support the concept of a reversible redox-sensitive linkage between LFA-1 and cytoskeleton by which oxidants and antioxidants may exert profound opposing effects on LFA-1 conformation and adhesive function.
authors.affiliation: Pathophysiology Division, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, USA. bedwards@salud.unm.edu
authors.forename: B S
authors.initials: BS
authors.lastname: Edwards
authors.forename: E A
authors.initials: EA
authors.lastname: Southon
authors.forename: M S
authors.initials: MS
authors.lastname: Curry
authors.forename: F
authors.initials: F
authors.lastname: Salazar
authors.forename: J M
authors.initials: JM
authors.lastname: Gale
authors.forename: M K
authors.initials: MK
authors.lastname: Robinson
authors.forename: L H
authors.initials: LH
authors.lastname: Graf
authors.forename: J L
authors.initials: JL
authors.lastname: Born
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000911:Antibodies, Monoclonal; D001152:Arsenicals / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000502:physiology*; D007694:Killer Cells, Natural / Q000502:physiology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000502:physiology*; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D015398:Signal Transduction; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013696:Temperature; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D001152:Arsenicals; D016023:Integrins; D016169:Lymphocyte Function-Associated Antigen-1; D016877:Oxidants; D013438:Sulfhydryl Compounds; C029341:oxophenylarsine; D010769:Phosphothreonine; D010768:Phosphoserine; D000255:Adenosine Triphosphate; D013755:Tetradecanoylphorbol Acetate